Research Of Conservation Tillage And Rotation Tillage Of Wheat Relayed Maize

This experiment was done in field of Zhongcun village, Zhongcun town, Longkou city, Shandong Province in 2005～2006. Five tillage patterns were studied in this experiment, including conventional tillage without straw returned (shorts for CT), conventional tillage with straw returned(shorts for CS), rotary tillage with straw returned (shorts for RS), no tillage with straw covered with straw covered (shorts for NS). On the base of these five tillage patterns, rotation tillage and different N fertilizer applied amount were studied. Effects of different tillage practice on crop growth, soil physical and chemical characters were studied. Combined with physiological and biochemical analysis, experiment was mainly about field research in effects of conservation tillage and rotation tillage on field ecological effects. Main results were was follows:First, effects on soil physical characters of tillage patternsSoil water content varied severely in soil surface layer and varied smoothly in depth layer under different tillage treatments. Soil water content declined before jointing stage and rised from jointing stage to maturity stage. Conservation tillage had obvious water saving effects before jointing stage while the water content of conservation tillage was lower than that of conventional tillage after jointing stage. There was almost no difference in the deep layer between conservation tillage and conventional tillage. The water content of conservation tillage was higher than that of conventional tillage. While in the late growth stage, the canopy became large, the water absorption ability of root became strong, and the vertical moving ability of water became obvious. Thus the water content of conservation tillage was 12% lower than that of conventional tillage. Thus water use efficiency of conservation tillage was 2.73kg/(hm2·mm) higher than that of conventional tillage. There was small difference between rotation tillage and corresponding tillage.Conservation had the effect of increasing soil temperature when it was hot and reducing soil temperature when it was cool, of which NS had the best regulating function. When it was only referred to CT and CS, straw returning had the function of regulating soil temperature. The function of regulating soil temperature in 10cm soil layer was later than in 5cm soil layer. This was because soil water content in that stage of regreening stage in 5~10cm was high, which lead to the slow change of soil temperature. Tillage had the bigger effect on the surface layer of soil, and the temperature range in 5cm was bigger than in 10cm which was also bigger than in 15cm. Soil temperature was increased after subsoiling tillage, especially temperature in 5cm and 10cm.Conservation tillage which had lower total porsity had higher soil bulk density in 0~20cm layer than conventional tillage, of which HS was the highest. The bulk density in 0~20cm layer was lower and porsity was higher in rotation tillage after subsoiling.Second, effects of tillage patterns on other soil chemical characters Straw returning could significantly increased soil respiration rate at the early stage after straw was incorporated into soil of getting-up stage, jointing stage and anthesis, and could reduced soil respiration rate in the later stage of wheat sowing stage and maturity stage. Soil respiration rate of conservation tillage was higher than that of conventional tillage all the wheat growth stage except at getting-up stage, and NS, HS had higher respiration rate, RS was lower. Soil respiration rate was negatively related to soil pondage and cappliary porsity at P=0.01 level and P=0.05 level. There was no significant relativity between soil temperature and soil temperature.The NO3--N declined before jointing stage and rised in maturity stage in the whole wheat growing season. The NO3--N content in 0~40cm soil layer of conservation tillage was higher than that of conventional tillage, among which NS was the highest; while in the deep layer the NO3--N content of conventional tillage was higher than that of conservation tillage. After subsoiling tillage was done, the NO3--N content of rotation was significantly higher than corresponding tillage. And the NO3--N content of RS×PS treatment was the highest, 39kg·hm-2and 97.42kg·hm-2higher than that of RS and CT respectively.In the condition of this experiment, the NH4+-N content in 0-100cm soil layer reached the highest value in wheat maturity stage, and HS and NS had the higher NH4+-N content in 0-100cm soil layer. RS and HS could increase NH4+-N content in 0~40cm in the later stages when wheat grow vigorously. While in 40~100cm layer, CT had higher NH4+-N content. The NH4+-N content of rotation tillage after subsoiling was lower than that of the corresponding tillage. There was no significant difference between tillage patterns in NH4+-N content in 0-100cm. But NH4+-N content in 0-100cm in tillage treatment was higher than corresponding rotation tillage treatments by 93.66 kg·hm-2 in average.Seen from whole wheat growth, the order of total nitrogen in 0~20cm from high to low was that CS>RS>CT>HS>NS; and in 20~40cm CT was higher than CS higher than minimum tillage higher than NS. The alkali-hydrolysable nitrogen of CS was higher than CT, higher than minimum tillage higher than NS and the difference in 20~40cm was bigger than that of in 0~20cm. The order of available phosphorous in 0~20cm of the whole wheat growth season was CT>CS>NS, and RS was the lowest. While in 20~40cm, available phosphorous of conservational tillage was higher than that of conservation tillage. And the difference in 0~20cm was bigger than in 20~40cm.Generally speaking, soil total nitrogen, alkali-hydrolysable nitrogen and available phosphorous was higher after subsoiling. This showed that subsoilig could break plough pan and increase the abortion of soil nutrient.Total amount of nitrogen fertilizer had lead to the waste of fertilizer, while half amount of nitrogen fertilizer lead to the decay of soil fertility. The most economic amount of nitrogen fertilizer was between half amount and total amount nitrogen.Third, effects of tillage patterns on crop growth and development.The wheat dry matter accumulation and kernel filling had the tendency of"S"type. From the simulation of Logistic growth equation, it could got that the average wheat filling rate of conservation tillage was higher than that of conventional tillage, while conventional tillage had highest maximum filling rate. The maximum filling rate of conventional tillage appeared 16 days after anthesis, and that of conservation tillage was two to four days later than conventional tillage. Seen from the transferring amount and transferring ratio, the transferring ratio of conventional tillage was 91% and conservation tillage was 69.2%, among which NS was the lowest. This showed that conservation tillage could increase transferring of photosynthate from nutrient organ to generative organ.There was no significant difference in wheat yield between tillage patterns, the yield of conventional tillage was higher and that of NS was the lowest. Among total amount of nitrogen fertilizer treatments, the order of wheat yield from high to low was that CT>HS>CS>RS>NS, but the difference was not significant. From the analysis of wheat yield and yield components, it could be seen that tillage patterns had significant effects on yield. The interact of fertilizer and tillage pattern had big effect on 1000 kernels weight and yield. Fertilizer was the most important variation source, whose affecting force was larger than the interact of fertilizer and tillage pattern. The affecting force of single tillage factor was smaller than that of fertilizer treatment.Conservation tillage could increase maize leaf index, and delayed the maximum filling rate for one day compared with conventional tillage. The yield of minimum tillage especially HS was significantly higher than that of conservation tillage and NS.The maize yield of rotation tillage after subsoiling was lower than that of corresponding tillage. Among which CT reduced the biggest extent, reached to 16.52%, and RS was following behind, reduced by 13.4%, HS reduced the least extent, only 1.16%. The reduce of spike number was the main reason of the reduce of wheat yield. Although subsoiling enhanced the soil physical and chemical characters, among which RS and HS was bettered much. Wheat yield was reduced.